Manufacture of artificial threads or the like



April 1939- o. EISENHUT ET AL 2,154,893

MANUFACTURE OF ARTIFICIAL THREADS OR THE LIKE Filed Feb. 15, 1936' Inven fors By mo r Afforneys Patented Apr. 18, 1939 UNITED STATES PATENToFFloE MANUFACTURE OF ARTIFICIAL THREADS OR THE LIKE ApplicationFebruary 15, 1936, Serial No. 64,084 In Germany February 15, 1935.

3 Claims.

Our present invention relates to the manufacture of artificial threadsor the like.

One of its objects is to provide an improved process of producingartificial threads films or 5 the like from viscose. Further objectswill be seen from the detailed specification following hereafter.

It is known that films, threads and the like made from viscose and notsubjected to a special aftertreatment have comparatively little strengthin wet condition. It has been attempted to increase the wet tenacity ofsuch materials by sub stituting for the aftertreatment the use of moreexpensive highly concentrated baths accompanied by stretching, wherebythe dry tenacity is increased; however, this process considerablydiminishes the extensibility of the material. Moreover, use of highlyconcentrated baths in itself involves certain technical difficulties andthe baths attack cellulose material so that the stability of thematerial is damaged.

According to this invention we have found that films, threads and thelike having a very high tensile strength in the wet state and also goodextensibility, may be produced from viscose if the viscose has beenripened so far as to have an ammonium chloride number below 7 to 6(Hottenroth number). In order to obtain the above effect, the threadmust be subjected to tension in a water bath or a bath containing anelectrolyte in strong dilution immediately following the coagulationbefore any or only after traces of cellulose have been regenerated, thatis to say while the thread still consists in the main part ofxanthogenate. It is essential that the decomposition of the xanthogenatetakes place only after the application of tension.

In this manner there is obtained a very homogeneous material which, inthe case of thread material, has a substantially cylindrical crosssection and does not show even under the highest magnification any orscarcely any difference of structure throughout the whole cross section.If the tension is applied too early, that is to say during thecoagulation, then the desired properties are produced to a feeble degreeor not at all. The viscose may be coagulated in the manner described inU. S. Patent No. 2,065,175 by means of water without any addition orwith addition of a. small quantity of a substance which assistscoagulation, while avoiding the use of expensive precipitating baths.Thus a spinning bath having a pH-value of 1.0 to 11 and an osmoticpressure corresponding at most with that of an aqueous solution of 1% ofsodium sulfate and 0.2%

of sufuric acid is suitable. The extension of the coagulated materialmay be carried out while the material dips into water or in watercontaining a small quantity of electrolyte. The pH-value of this bathmay have the same values as the 5 spinning bath, however, it may be evenless than one, so as to correspond with a sulfuric acid content of 1-2%,that is to say, to a pH-value of about 0.8.

With a degree of ripeness corresponding with 19 a Hottenroth number of 2to 1 the'temperature of the water is preferably about 20 C.; if theviscose has been more strongly ripened it is possible to spin even withwater of 0 C. If the viscose has been less ripened the spinning bath mayhave a temperature of 25 C. and more. When spinning threads the bath inwhich the tension is applied contains preferably traces or a smallquantity of electrolyte in order to avoid sticking of the single fibers(for instance, there is used sulfuric acid of 1 to 2 per cent).Thetension which is applied to the thread may be produced in variousmanner, for instance, by bending the thread so that no essentialpermanent extension of the thread occurs. After having exposed thethread to thetension for producing the high tensile strength in the wetstate the xanthogenate is decomposed in the usual manner by means ofdilute sulfuric acid with or without the addition of salt whereby lesserconcentrations of the decomposing bath than usual may be applied becauseof the' strong self-decomposition of the xanthogenate due to theextremely strong ripening of the viscose.

In the accompanying drawing there is shown an arrangement for spinningin accordance with the invention.

The viscose enters at l into a spinning head and is guided to thespinning nozfile 2. The precipitating liquid enters the spinning headthrough 40 the tube 3 and flows through the spinning funnel 4. In thespinning funnel the viscose is coagulated. When leaving the spinningfunnel 4 the thread 8 enters a bath 1 in which rods 9 are provided forimparting tension to the thread 8.

grams per denier wet, with an extension of 16 per cent. and 18 per cent.respectively. Artificial having 90 perforations, each 0.8 mm. wide, into7 a funnel 55 cms. long, the speed of draft being 50 meters per minuteand the precipitating bath being water at 22 0.; directly after leavingthe funnel the thread and the precipitating water pass into a vesselinto which acid has been added, drop by drop, so that the liquid has apH-value of about 2. For the purpose of producing a tension the threadis guided over rods to the bottom of the vessel and then up again andfinally wound on a reel, while being treated with acid.

The threads thus obtained and having a titer of 3.5 show the followingdata:

Dry tenacity grams per denier..- 2.5- 2.6 Wet tenacity do 1.8- 1.9Extension, dry per cent 15.3 Extension, wet do 16.2

Example 2.When operating as described in Example 1 but bending thethread 4 times for applying tension there is obtained a material whichhas the same titer as the thread obtained according to Example 1,however it has the following properties:

Tensile strength in the dry state gr./denier 2.8 Tensile strength in thewet state do 2.3 Extensibility in the dry state per cent 10.5Extensibility in the wet state do 10.1

. What we claim is:

1. A process of producing artificial film threads and the like of hightensile strength which comprises coagulating viscose having a degree ofripening corresponding with an ammosure of which corresponds at mostwith thatof an aqueous solution of 1 per cent of sodium suifate and 0.2per cent of sulfuric acid, said solu-- tion having a pH-value of between0.8 and 11 while avoiding material permanent extension. and decomposingthe material to cellulose hydrate after the applicaiton of tension.

2. A process of producing artificial iilms, threads and the like of hightensile strength which comprises coagulating viscose having a degree ofripening corresponding with an ammonium chloride number below 7 in anaqueous spinning bath having a pH-value of 1.0 to 11 and an osmoticpressure corresponding at most with that of an aqueous solution of 1% ofsodium sulfate and 0.2% of sulfuric acid to form xanthogenate containingat most traces of regenerated cellulose, subjecting the coagulatedmaterial to tension in an aqueous liquid having a pH-value of 0.8 to 11and an osmotic pressure corresponding at most with that of an aqueoussolution of 1% of sodium sulfate and 2% of sulfuric acid while, avoidingmaterial permanent extension, and decomposing the material to cellulosehydrate after the application of tension.

3. A process of producing artificial threads of high tensile strengthwhich comprises spinning viscose having a degree of ripenesscorresponding with an ammonium chloride number of 1.4 into a spinningbath of water heated at 22 C. and circulated through a spinning funnel,guiding the spinning bath and the threads into a vessel, mixing saidspinning bath with sulfuric acid to have a pH-value of about 2, applyingstretch to said threads while in said mixture of sulfuric acid with thespinning bath and winding the threads on a receiving device, whiletreating them with acid.

' O'ITO EISENHUT.

HANNS REIN. HUGO WIDMANN.

